NovoTTF™-100A System (Tumor Treating Fields) transducer array layout planning for glioblastoma: a NovoTAL™ system user study

Abstract

BackgroundOptune™, previously known as the NovoTTF-100A System™, generates Tumor Treating Fields (TTFields), an effective anti-mitotic therapy for glioblastoma. The system delivers intermediate frequency, alternating electric fields to the supratentorial brain. Patient therapy is personalized by configuring transducer array layout placement on the scalp to the tumor site using MRI measurements and the NovoTAL System. Transducer array layout mapping optimizes therapy by maximizing electric field intensity to the tumor site. This study evaluated physician performance in conducting transducer array layout mapping using the NovoTAL System compared with mapping performed by the Novocure in-house clinical team.MethodsFourteen physicians (7 neuro-oncologists, 4 medical oncologists, and 3 neurosurgeons) evaluated five blinded cases of recurrent glioblastoma and performed head size and tumor location measurements using a standard Digital Imaging and Communications in Medicine reader. Concordance with Novocure measurement and intra- and inter-rater reliability were assessed using relevant correlation coefficients. The study criterion for success was a concordance correlation coefficient (CCC) >0.80.ResultsCCC for each physician versus Novocure on 20 MRI measurements was 0.96 (standard deviation, SD ± 0.03, range 0.90–1.00), indicating very high agreement between the two groups. Intra- and inter-rater reliability correlation coefficients were similarly high: 0.83 (SD ±0.15, range 0.54–1.00) and 0.80 (SD ±0.18, range 0.48–1.00), respectively.ConclusionsThis user study demonstrated an excellent level of concordance between prescribing physicians and Novocure in-house clinical teams in performing transducer array layout planning. Intra-rater reliability was very high, indicating reproducible performance. Physicians prescribing TTFields, when trained on the NovoTAL System, can independently perform transducer array layout mapping required for the initiation and maintenance of patients on TTFields therapy.

Tumor-Treating Fields: A Fourth Modality in Cancer Treatment

“…In GBM, patient MRI data are used to individualize the transducer array placement, maximizing field intensity at the target tissue (38). This is achieved using treatment planning software (Novo-TAL, Novocure Ltd.) that allows the treating physician to use cranial morphometry and tumor location to output a personalized configuration of transducer arrays (39)(40)(41). Specifically, simulations of TTFields delivery to the head (or other anatomic regions) are performed using realistic computerized models generated by Sim4Life V3.0 (ZMT-Zurich) electroquasi-static solver.…”

Planning TTFields treatment using the NovoTAL system-clinical case series beyond the use of MRI contrast enhancement

“…The NovoTAL System is an algorithmic software program that creates optimal transducer array layouts based on patient head size and tumor location measurements obtained from an MRI [11]. Electric field distribution within the brain is nonuniform, and is a function of the direction of a field, individual dielectric properties of adjacent tissue structures, and the orientation of the interfaces between them [9, 10].…”

“…The algorithm will compute the optimal paired configuration of transducer arrays that should be applied directly to a patient’s shaved scalp that will locally deliver the highest intensity of TTFields at the site of a tumor. The NovoTAL System was FDA approved in 2013 on the basis of a user study that included a total of 14 neuro-oncologists, neurosurgeons, and medical oncologists who were trained on treatment planning and then had to independently generate treatment maps for 5 blinded GBM cases [11]. The concordance between physician mapping and gold-standard in-house mapping performed by the manufacturer’s clinical team was excellent, with an R 2 -correlation coefficient for 20 individual measuring parameters exceeding 0.99.…”

“…As the frequency of TTFields is much lower at 200 kHz, and the wavelength much longer (~1 mile), TTFields cannot be precisely focused and delivered to discrete regions of the brain in the same focal manner as RT [9, 10]. Treatment can, however, be optimized to ensure that field intensity is maximal at the site of a tumor [11–13], a process which involves planning with the NovoTAL System software.…”

“…The methods for performing treatment planning have been described previously [11], but in brief, consist of obtaining 20 measurements delineated on T1 postcontrast sequences from the patient’s most recent MRI scan. Coordinate dimensions are obtained for head size using T1 postcontrast sequences, on a slice at the superior level of the orbit.…”